From a basic science and health point of view, it is not advisable to sleep under a tree at night mainly because the tree releases which gas at that time?

Introduction / Context:
Many traditional pieces of advice about health and environment have a basis in elementary science. One such common advice is that people should avoid sleeping under trees at night. This question asks about the scientific reason behind that advice by focusing on which gas is released by trees in the dark that can affect air quality around a sleeping person.

Given Data / Assumptions:

- The situation described is sleeping under a tree at night. - We must identify the gas released by the tree that makes this inadvisable. - Options mention oxygen in lesser quantity, oxygen in large amounts, carbon monoxide and carbon dioxide. - The explanation draws on basic plant physiology and respiration.

Concept / Approach:
During the day, in sunlight, plants carry out photosynthesis, using carbon dioxide and releasing oxygen. At night, photosynthesis stops due to lack of light, but respiration in plants continues. During respiration, plants take in oxygen and release carbon dioxide, just like animals do. Under a dense canopy on a still night, carbon dioxide concentration can increase slightly near the ground, while oxygen availability can be reduced compared to open surroundings. Therefore, the gas mainly released that justifies the warning is carbon dioxide.

Step-by-Step Solution:
1. Recall that photosynthesis requires light, chlorophyll, carbon dioxide and water to produce glucose and oxygen. 2. In the absence of light at night, photosynthesis stops, so trees no longer convert carbon dioxide into oxygen. 3. However, respiration in plant cells continues all the time and involves taking in oxygen and releasing carbon dioxide. 4. When someone sleeps very close to a large tree, especially under a dense canopy, the local concentration of carbon dioxide in the still air can rise. 5. Therefore, the main gas released by trees at night that can cause discomfort or mild suffocation risk is carbon dioxide. 6. Thus, carbon dioxide is the correct answer.

Verification / Alternative check:
Basic biology textbooks clearly state that in darkness, plants only respire and do not photosynthesise, which means they release carbon dioxide instead of oxygen. Simple classroom experiments measuring gas exchange in light and dark conditions confirm this behaviour. The traditional advice about avoiding sleeping under trees at night is often explained in school science lessons using this same reasoning. These multiple lines of evidence support the choice of carbon dioxide as the correct option.

Why Other Options Are Wrong:
Oxygen in a lesser quantity than required is an imprecise statement and does not identify the specific gas of concern. Oxygen in large amounts is actually beneficial for breathing, so it cannot be a reason to avoid sleeping under a tree. Carbon monoxide is a toxic gas generally produced by incomplete combustion of fuels and is not released in significant quantities by trees. Therefore, these three options do not accurately describe the main gas involved in this situation.

Common Pitfalls:
Some candidates may misinterpret the question and think only in terms of reduced oxygen rather than increased carbon dioxide. Others may confuse carbon monoxide with carbon dioxide because both names sound similar, even though carbon monoxide is related to pollution from vehicles and stoves, not to plant respiration. To avoid such mistakes, it is important to remember the basic equation of respiration as using oxygen and releasing carbon dioxide, and to link that directly with this classical general science question.

Final Answer:
It is not advisable to sleep under a tree at night mainly because the tree releases carbon dioxide during respiration in the dark.